CD200, also known as OX-2 membrane glycoprotein isoform a, is a transmembrane immuno- regulatory protein that belongs to the immunoglobulin superfamily. Its receptor (CD200R) is restricted primarily to mast cells, basophils, macrophages, and dendritic cells, which suggests myeloid cell regulation as the major function of CD200. Elevated expression of this protein has been reported to be associated with poor prognosis in a number of human malignancies. In addition, it also plays an important role in prevention of graft rejection, autoimmune diseases and spontaneous abortion. Recombinant human CD200 protein, fused to hIgG-His-tag at C-terminus, was expressed in insect cell and purified by using conventional chromatography techniques.